Vibrating microtomes in which the cutting edge performs an oscillating horizontal motion along the direction of the cutting edge, while the material being sectioned advances in the other horizontal direction and is thus sectioned along a horizontal sectioning surface, are well known, for example from the Applicant's DE 196 45 107 C2 and DE 20 2004 007 658 U1. Vibrating microtomes of this kind are used in particular to section tissue specimens in liquids (buffer solutions), for example brain tissue, or other materials of low plastic stability and/or gel-like consistency. In one usual geometry, the sample is fed forward vertically (Z axis) and stepwise from bottom to top. During an individual sectioning operation, the knife moves at the sectioning speed horizontally (X axis) with respect to the sample. In that context, it vibrates substantially parallel to the cutting edge in a vibration direction that is perpendicular (Y axis) to the other motion directions, the vibration frequency being typically on the order of 100 Hz, for example in the range from 90 to 100 Hz. Because of the tolerances of the knife holder and knife, however, it is inevitable that the knife edge does not move exactly parallel to the vibration direction. A knife that is clamped in obliquely produces, because of the vibration, a corresponding motion in the Z direction; this transverse vibratory offset (i.e. perpendicular to the section plane, thus extending in the Z direction in this case) is also referred to as vertical runout. The consequence of a vertical runout is that the sections exhibit a wave-like pattern.
An electrical control system of a vibrating microtome is described in the article “Patch-clamp recording in brain slices with improved slicer technology,” Pflügers Arch—Eur. J. Physiol. (2002) 443:491-501 by J. R. P. Geiger et al., who propose a measuring head (referred to as a “vibroprobe”) as an aid to determining the transverse offset occurring in the context of knife oscillation. The measuring head operates with an IR light beam that is emitted by an LED and detected in a photodiode, and measures the magnitude, or the change over time in said magnitude, of the (partial) coverage of the light beam by the cutting edge positioned in the beam path. The vertical runout occurring as a consequence of the oscillating motion of the cutting edge thus yields an oscillating output signal whose vibration amplitude is to be minimized by appropriate manual adjustment of the alignment of the cutting edge. By means of a setting screw (for tilting the knife), the knife edge is aligned parallel to the vibration direction and the vertical runout of the knife is thus reduced to a minimum. This operation of aligning the knife edge is time-consuming and cumbersome, not least because pivoting of the knife is generally associated with a realignment of the Z position. A rapid alignment operation, on the other hand, is of great advantage, given that the samples are short-lived and must be processed quickly.